I recently bought a 44 Mag flattop. It has a 4 5/8 in barrell. How common are these short barrels on a 44 Mag? Would it have been done at Ruger? It is a 1958 model TY W Opp

Thinking it may be after market.

According to John Taffin the original flat tops were 6 1/2, 7 1/2 and 10”. So a 4 5/8” would either have been cut down or replaced.

It may be an original barrel that was cut down or may have been a replacement barrel. Definitely not correct. A pic of the left side of the barrel, including the front sight would tell us what it is.

My first in 1956 was 7-1/2" but you still have a great gun. The original started at 6-1/2". To get the most from the powder, short loses some velocity. Might have been the consideration at the time. Mine was $96 and was deadly to over 600 yards on rocks at a RR bank. Funny to see the whole barrel above the rear Micro sight. I inlayed silver wires in the front but ran out fast. The big 429421 bullet had a huge arc with 22 gr of 2400. I eventually got the S&W 29 for $140 and it shot well but I never got used to the grip. Both guns would do 1/2" at 50 yards but if I put the S&W down and picked it up again, the group moved as much as 10". Still tight but a different place. Then I shot IHMSA with a 10-1/2" Ruger to win just about every shoot and Ohio state with 79 out of 80. I missed the last 200 meter ram. I still have the gun with well over 96,000 rounds with no wear I can measure. I use STP oil treatment on the pin and ratchet.
Recoil was fierce with the old factory loads that I had to use for brass but my loads were not as bad. I had dies and the mold before the gun arrived from Klein's Sporting Goods in the mail. Yes a kid could get a revolver in the mail.
We shot one time at a quarry and a guy stopped to meet us and said he had a powerful gun, P38----Yeah. There was a 55 gallon drum close so I handed him my Ruger and told him to shoot the drum. He did but the barrel stopped an inch from his head, he was white as a ghost, handed the gun back and left without a word.

According to John Dougans guide to Ruger Single Actions;

44's were first shipped in 1956. All had 6 1/2" barrels. 7 1/2 & 10" barrels started appearing in 1959 @ s/n 17,xxx plus. No other barrel lengths mentioned.

Original or not, that is a great carrying & using revolver. You realize, of course, you must post a photo to avoid being pelted with vegetables?

I sold a 6.5 last week from 1958. Many times I thought about shortening it. Glad I didn't but that wouldn't have stopped me from buying one if I'd have found one...

I'll try to load a photo